title: Differential expression of proteins in naïve and IL-2 stimulated primary human NK cells identified by global proteomic analysis.
abstract: Natural killer (NK) cells efficiently cytolyse tumors and virally infected cells. Despite the important role that interleukin (IL)-2 plays in stimulating the proliferation of NK cells and increasing NK cell activity, little is known about the alterations in the global NK cell proteome following IL-2 activation. To compare the proteomes of naïve and IL-2-activated primary NK cells and identify key cellular pathways involved in IL-2 signaling, we isolated proteins from naïve and IL-2-activated NK cells from healthy donors, the proteins were trypsinized and the resulting peptides were analyzed by 2D LC ESI-MS/MS followed by label-free quantification. In total, more than 2000 proteins were identified from naïve and IL-2-activated NK cells where 383 proteins were found to be differentially expressed following IL-2 activation. Functional annotation of IL-2 regulated proteins revealed potential targets for future investigation of IL-2 signaling in human primary NK cells. A pathway analysis was performed and revealed several pathways that were not previously known to be involved in IL-2 response, including ubiquitin proteasome pathway, integrin signaling pathway, platelet derived growth factor (PDGF) signaling pathway, epidermal growth factor receptor (EGFR) signaling pathway and Wnt signaling pathway.
  
  
  CONCLUSIONS
  The development and functional activity of natural killer (NK) cells is regulated by interleukin (IL)-2 which stimulates the proliferation of NK cells and increases NK cell activity. With the development of IL-2-based immunotherapeutic strategies that rely on the IL-2-mediated activation of NK cells to target human cancers, it is important to understand the global molecular events triggered by IL-2 in human NK cells. The differentially expressed proteins in human primary NK cells following IL-2 activation identified in this study confirmed the activation of JAK-STAT signaling pathway and cell proliferation by IL-2 as expected, but also led to the discovery and identification of other factors that are potentially important in IL-2 signaling. These new factors warrant further investigation on their potential roles in modulating NK cell biology. The results from this study suggest that the activation of NK cells by IL-2 is a dynamic process through which proteins with various functions are regulated. Such findings will be important for the elucidation of molecular pathways involved in IL-2 signaling in NK cells and provide new targets for future studies in NK cell biology.
authors.affiliation: School of Pharmacy, University of Wisconsin-Madison, 777 Highland Ave., Madison, WI 53705, USA.
authors.forename: Di
authors.initials: D
authors.lastname: Ma
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI 53706, USA.
authors.forename: Weifeng
authors.initials: W
authors.lastname: Cao
authors.affiliation: Department of Obstetrics and Gynecology, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI 53792, USA.
authors.forename: Arvinder
authors.initials: A
authors.lastname: Kapur
authors.affiliation: Department of Obstetrics and Gynecology, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI 53792, USA.
authors.forename: Mildred
authors.initials: M
authors.lastname: Felder
authors.affiliation: School of Pharmacy, University of Wisconsin-Madison, 777 Highland Ave., Madison, WI 53705, USA.
authors.forename: Cameron O
authors.initials: CO
authors.lastname: Scarlett
authors.affiliation: Department of Obstetrics and Gynecology, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI 53792, USA.
authors.forename: Manish S
authors.initials: MS
authors.lastname: Patankar
authors.affiliation: School of Pharmacy, University of Wisconsin-Madison, 777 Highland Ave., Madison, WI 53705, USA.|Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI 53706, USA.
authors.forename: Lingjun
authors.initials: L
authors.lastname: Li
mesh_terms: D015703:Antigens, CD / Q000378:metabolism; D049109:Cell Proliferation; D066246:ErbB Receptors / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D016023:Integrins / Q000378:metabolism; D007376:Interleukin-2 / Q000378:metabolism*; D007694:Killer Cells, Natural / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D020543:Proteome / Q000378:metabolism*; D040901:Proteomics; D015398:Signal Transduction; D025801:Ubiquitin / Q000378:metabolism; D051153:Wnt Proteins / Q000378:metabolism
chemical_list: D015703:Antigens, CD; D016023:Integrins; D007376:Interleukin-2; D010982:Platelet-Derived Growth Factor; D020543:Proteome; D025801:Ubiquitin; D051153:Wnt Proteins; D066246:ErbB Receptors
keywords: IL-2 signaling; Lab-free quantification; Mass spectrometry pathways; Multi-dimensional separation; NK cells; Proteomics